Question

Tính nhanh: A= 3.136. 8+ 4.14. 6- 14.150

                  C= 1/10 + 1/15 + 1/21...........+1/120

Answer 1

A= 3.136.8+4.14.6- 14.150

  =  24.136+24.16- 14.150

  = 24. (136+14)- 14. 150

  = 24. 150- 14.150

  = 150. (24-14)=150. 10= 1500

Answer 2

A=  24.136 + 24.14 - 14.150

  = 24.(136 + 14)- 14.150

  =  24.150 - 14.150

  = 150. (24- 14)=150.10 =1500